The runic script first appears in the northwest of Germany in the first
century AD. Where the runes came from is up for debate, but very few scholars
will claim that they developed on their own in Germany without influence.
Supporting a possible "spontaneous generation" might be the fact
that the earliest runic inscriptions date to that first century AD, and they are
found in the northwest portion of Germany. At this particular point in history,
the main alphabets that could have influenced the script were the Latin and
Greek alphabets, both of which really only show a passing resemblance to the
Germanic script.
Interestingly, it is a non-Indo-European script that is usually pointed to as
the source: the Etruscan alphabet. A quick comparison reveals identical (or
nearly so) symbols for a variety of letters, including (but not limited to) U,
A, C (k), I, T, M, L, and D. The ratio of identical letters to total letters
(10:24) is enough to show possible descent.¹
The runes appear to have been used from the first century AD until
approximately 1100 AD² (though arguments can be made to stretch this into the
1800's, where the
Dalecarlian runes finally go extinct). The period from 100 AD
until 600 AD is usually thought of as the "older runic inscriptions",
but this varies by geography.
It is probably easiest to say, "Where there were speakers of a Germanic
language during these time periods, there were runes," for they are found
in all Germanic languages developed during this time. There are even
arguments that the famous Kensington
Runestone (most likely a forgery) is, in fact, real, putting the geography
of runes stretching as far west as Minnesota. Realistically, we can say that
runes were used in Denmark, Sweden, Norway, Iceland, Germany, Poland, Russia, Hungary,
Romania, and the British Isles.³
The runes appear to have been used exclusively in Germanic-speaking
countries, but I have speculation from Tacitus' Germania that the runes
may have been used by Celts near the Rhine or in Belgium as well. Given Tacitus'
proclivity for mixing up the Germans and the Gauls, it is entirely possible that
chapter 10 of the Germania is actually about a Gaulish tribe. I would not
say, though, that the use might have been extensive enough to be considered
truly "cross-cultural."†
Sources:
¹ - Elliott, Ralph W. V. Runes: an Introduction. New York: St. Martin’s Press. 1989.
p. 8
² - Page, R. I. Runes. London: British Museum Publications. 1987.
p. 9
³ - Page, R. I. Runes. London: British Museum Publications. 1987.
p. 10
† - Tacitus, Cornelius. The Life of Agricola and The Germania.
William Francis Allen, ed. Boston: The Athenaeum Press. 1913.